This proposal describes a five year training program for the development of an academic career in Vascular Surgery for the Principal Investigator, who has completed a structured residency in Vascular Surgery at the Beth Israel Deaconess Medical Center / Harvard Medical School and is currently an Assistant Professor of Surgery in the tenure track at the Mount Sinai School of Medicine. The Mentored Scientist Clinical Development Award will support the development of the Principal Investigator, a vascular surgeon who is trained in experimental methods, into an independent investigator. The program will allow him to expand his expertise in vascular surgery research to develop, coordinate and translate laboratory findings into practical clinical applications for the endovascular treatment of patients with abdominal aortic aneurysms. The program will be performed under the mentorship of Valentin Fuster, M.D., Ph.D.. He is the past-president of the American Heart Association, Chairman of the Fellowship Training Directors Program of the American College of Cardiology and Director of the Cardiovascular Institute at the Mount Sinai Medical Center and a Professor of Medicine at the Mount Sinai School of Medicine. He has trained 38 research fellows, many of whom now direct independent laboratories. Juan Badimon, Ph.D., Professor of Medicine, will provide further supervision and training in the areas of thrombus formation and organization. Michael Marin, M.D., Professor of Surgery, a leading pioneer of endovascular stent graft treatment of abdominal aortic aneurysms will enhance the clinical applicability of the hypotheses to be tested. The focus of the research will be measuring the efficacy of endovascular stent graft treatments of abdominal aortic aneurysms. Abdominal aortic aneurysms are a leading cause of death due to aneurysm rupture. Although surgery is the only effective treatment, endovascular surgical techniques utilizing stent grafts have reduced the morbidity of repairing abdominal aortic aneurysms considerably. Endovascular treatments are designed to eliminate arterial perfusion of the aneurysm and thereby eliminate the risk of aneurysm rupture. Although significant advances have been made, the effectiveness of endovascular treatments in eliminating pressure within the aneurysm has not been definitively demonstrated. In addition, no non-invasive means of confirming successful and ongoing elimination of pressure from the aneurysm has been developed. The study will use an experimental model of abdominal aortic aneurysm with an implanted pressure transducer, developed in the principal investigator's laboratory. The effect of retrograde perfusion of the aneurysm sac on intra-aneurysmal pressure after treatment with an endovascular stent graft will be evaluated. The impact of stent graft porosity on the transmission of pressure to the aneurysm will also be studied. Pressure within the aneurysm sac will be correlated with the change in the cross-sectional area and volume of the aneurysm during systole and diastole using cine magnetic resonance imaging. This information may provide a non-invasive means of confirming the success of endovascular stent graft treatment in eliminating pressure from the aneurysm. The rich academic environment provided by the Mount Sinai School of Medicine and the Departments of Surgery and Medicine / Cardiology with the diverse resources and enthusiasm for promoting scientific research will maximize the potential for the principal investigator to establish an academic career as a clinician scientist.